Since then, Warren has said that the candidates should have additional debates in other parts of the state. On Friday, she challenged Brown to a debate in Worcester, hosted by the Colleges of Worcester Consortium, the Worcester Regional Chamber of Commerce, and the Telegram and Gazette. On Monday, Warren challenged Brown to a debate in New Bedford, sponsored by the SouthCoast Alliance, a coalition of business, civic, media and community service organizations.

"The people of Massachusetts share common concerns about the economy, education and keeping our commitments to seniors. But there are also local issues that weigh heavily on residents where the federal government has a role, such as South Coast Rail," said Warren campaign manager Mindy Myers, referring to a project to restore rail service from Boston to the south coast. "Elizabeth believes that voters should hear from both candidates on issues close to home in forums close to home."

Brown spokeswoman Alleigh Marre said Brown has already accepted more debates than any other incumbent Massachusetts senator in 16 years, including the four televised debates that Warren had requested and two additional radio debates, which Warren has not accepted. “This concludes the 2012 debate schedule,” Marre said. “These forums will provide voters across the Commonwealth with a stark contrast between Scott Brown's independent leadership and pro-jobs agenda, and Elizabeth Warren's extremely liberal tax and spend philosophy.”

Brown also declined to accept a debate proposed by Vicki Kennedy, the widow of former Sen. Edward Kennedy, and sponsored by the University of Massachusetts Boston and the Edward M. Kennedy Institute for the United States Senate, after Kennedy would not agree to remain neutral in the race.

Update: Late Monday, Brown responded by criticizing Warren for refusing to participate in a radio debate hosted by WBZ. Brown said he will appear on the radio show without Warren. "I'm disappointed that, after clamoring for debates, Elizabeth Warren has decided to duck the first opportunity of this campaign to discuss the issues with me at WBZ Radio Wednesday night," Brown said in a statement.